The present invention relates, in general, to electronics, and more particularly, to methods of forming semiconductor devices and structure.
In the past, the semiconductor industry utilized various methods and circuits to implement switching power supply systems and controllers. In order to minimize power dissipation, some implementations would switch the power transistor at a lower frequency or may even switch the power transistor on and off in short bursts. One such implementation to minimize power dissipation was disclosed in U.S. Pat. No. 6,252,783 issued to Dong-Young et al on Jun. 26, 2001.
One problem with such implementations was audible noise typically in the frequency range of about twenty to twenty thousand (20-20,000) Hz. When the switching frequency of the power transistor was reduced, it often produced noise in the audible frequency range. The audible noise was often objectionable and became a nuisance to users of the power supply.
Accordingly, it is desirable to have a switching power supply that has reduced power dissipation, and that minimizes audible noise.
For simplicity and clarity of illustration, elements in the figures are not necessarily to scale, and the same reference numbers in different figures denote the same elements. Additionally, descriptions and details of well-known steps and elements are omitted for simplicity of the description. As used herein current carrying electrode means an element of a device that carries current through the device such as a source or a drain of an MOS transistor or an emitter or a collector of a bipolar transistor, and a control electrode means an element of the device that controls current through the device such as a gate of an MOS transistor or a base of a bipolar transistor.